package com.starsky.common.utils;

import org.apache.commons.lang3.StringUtils;

/**
 *@desc: 过滤特殊字段
 *@author: wangsh
 *
 */
public class EmojiUtil {

    /**
     * 检测是否有emoji字符
     */
    public static boolean containsEmoji(String source) {
        if (StringUtils.isBlank(source)) {
            return false;
        }
        int len = source.length();
        for (int i = 0; i < len; i++) {
            char codePoint = source.charAt(i);
            if (isEmojiCharacter(codePoint)) {
                //do nothing，判断到了这里表明，确认有表情字符
                return true;
            }
        }
        return false;
    }

    private static boolean isEmojiCharacter(char codePoint) {
        return (codePoint == 0x0) ||
                (codePoint == 0x9) ||
                (codePoint == 0xA) ||
                (codePoint == 0xD) ||
                ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
                ((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) ||
                ((codePoint >= 0x10000) && (codePoint <= 0x10FFFF));
    }

    /**
     * 过滤emoji 或者 其他非文字类型的字符
     */
    public static String filterEmoji(String source) {
        source = source.replaceAll("[\\ud800\\udc00-\\udbff\\udfff\\ud800-\\udfff\\u2006]", "");
        if (!containsEmoji(source)) {
            return source;//如果不包含，直接返回
        }
        //到这里铁定包含
        StringBuilder buf = null;

        int len = source.length();

        for (int i = 0; i < len; i++) {
            char codePoint = source.charAt(i);

            if (isEmojiCharacter(codePoint)) {
                if (buf == null) {
                    buf = new StringBuilder(source.length());
                }
                buf.append(codePoint);
            } else {
                buf.append("");
            }
        }
        //如果没有找到 emoji表情，则返回源字符串
        if (buf == null) {
            return source;
        }
        //这里的意义在于尽可能少的toString，因为会重新生成字符串
        if (buf.length() == len) {
            buf = null;
            return source;
        } else {
            return buf.toString();
        }
    }

}
